In the industrial field, especially in the machine industry, various types of cleaners are used in large quantities to remove machining or preservative oils from machine parts. Recently, efforts such as the use of water-soluble cleaners have begun to be taken to reduce environmental burdens, but more efforts are still needed. Oils used in the machine industry are used for lubrication in machining (e.g., press working) or for protection against rust during storage and have to be highly viscous or adherent. This makes them difficult to be removed. Oils that are difficult to be removed from machine parts significantly affect the subsequent processes other than washing, such as welding, secondary processing, painting, plating and bonding, and also affect the washing system itself when washing is performed.